Interaction of Hydrogen with Actinide Dioxide (011) Surfaces

The
hydrogen catalysed oxidation of nuclear materials has led to containment vessel
failure. The interaction of hydrogen with actinide dioxide (AnO2, An
= U, Np, Pu) (011) surfaces has been completed by DFT+U; where, spin-orbit
interactions and noncollinear 3k antiferromagnetic behaviour have been included.
The energy of atomic hydrogen adsorption for UO2 (0.44 eV), NpO2
(-0.47 eV), and PuO2 (-1.71 eV) has been calculated, where the subsequent
formation of an OH group is shown to distort the surface structure. The
dissociation of hydrogen on the PuO2 (011) surfaces has been found;
however, UO2 (011) and NpO2 (011) surfaces are relatively
inert. The recombination of hydrogen ions on the UO2 (011) and NpO2
(011) surfaces is highly-probable; whereas, hydroxide formation on the PuO2
(011) surface has been shown. The results have consequences for fuel storage
management.